Originally posted by Asmosis:

When No Man's Sky did its first procedural terrain change, the new did replace the old.

Given that the terrain is generated from the algorithm first then player edits are applied to it, if they changed how world generation works, you wont have the old stuff as i don't believe Valheim saves the actual world state at all, just your changes.

Not that i think they will do this, they have placeholders already there for all the future planned biomes so there's no point in upsetting things.

No man's sky uses a VERY unique algorithm. Every time you load you are actually reloading those terrains as fresh (look at the frustration of players having terrain regenerate into base builds)

Nearly all other games load terrain changes before base changes, and my experience tinkering on valheim makes me think it is the latter.

I'd love to be wrong on this one but it is unlikely, since the guide says new saves may be needed for a couple features.